In the field of lighting, light fixtures are needed in many different settings, including high fixture positions for the most efficient use of light. Light fixtures for roadways, parking lots and other large outdoor areas typically use plug twist-lock photoelectric controllers (referred to herein as “photocontrols”) to automatically switch light fixtures on at dusk and off at dawn. These devices sense the intensity of the ambient light and switch the fixtures on and off accordingly. For best performance, photocontrols need to be oriented such that the cell faces in the direction of north in the northern hemisphere and south in the southern hemisphere, away from direct sunlight. It is desirable that photocell receptacles permit adjustment to the desired orientation.
For most uniformity throughout the lighting industry, electrical receptacles for receiving photoelectric controllers are mostly made according to specific requirements approved by American National Standards Institute, Inc. (ANSI). Such receptacles are typically mounted on the top of light-fixture housings and are electrically wired into the power supply for the light fixtures. A photoelectric controller is plugged into each receptacle to provide photoelectric control for the light fixture.
FIGS. 11 and 12 show an example of a common photocontrol unit 11 having three standard conductors in the form of prongs 110 which are inserted into corresponding openings 301 in the receptacle by applying downward pressure on the photocontrol casing. After the prongs are completely inserted, the controller is rotated to lock it in place. As more light fixtures use light emitting diodes (LEDs), many of such fixtures are also being configured for a dimming option which can be controlled via different methods, including wirelessly.
ANSI has recently approved a set of standards for making photocontrols and receptacles that are configured for up to four new conductors in addition to the three standard conductors. The new conductors provide electrical connections that accommodate additional control features such as dimming. As seen in FIG. 6 of ANSI C136.41-2013 standards, such new conductors may be in the form of conductive spring(s) on the photocontrol unit and corresponding conductive plate(s) on the receptacle.
After insertion in the receptacle, both types of photocontrols, i.e., the standard three-prong and the new five- or seven-prong photocontrols, should be orientated in the appropriate direction to optimize the operation of the photoelectric cell.
There have been several prior arrangements for mounting photocontrol receptacles to light fixtures and adjustment of the receptacle orientation to provide appropriate plugged-in photocontrol orientation.
In some prior arrangements, orientation adjustment is achieved by loosening screws that secure the receptacle to the light fixture, rotating the receptacle until an arrow or other indicia is aimed generally toward north, and then re-tightening the screws. Such operation requires certain disassembling of the receptacle and the challenge of not changing the desired receptacle orientation while re-tightening the screws.
Some other prior receptacles are resiliently attached to the light-fixture housing surface using a snap ring. In such arrangements, the orientation adjustment is achieved by lifting the receptacle to disengage it from the fixture housing and turning the receptacle to a desired orientation. However, lifting of the receptacle also disengages weather sealing that protect the fixture housing interior from the elements. This presents a difficulty of ensuring that the weather seal is functioning properly to prevent water from entering the housing.
Certain of the prior assemblies require significant room inside the fixture housing to accommodate mounting of the receptacle. Many recent LED light fixtures have considerably slimmer profiles than prior light fixtures that used non-LED light sources. Therefore, LED light fixtures have very limited room inside their housings.
Thus, there is a need for simple mounting assembly which takes minimal interior space and permits easy tool-less orientation while maintaining weather seals that prevent water from entering the light-fixture housing.